JPH0980065A - Rotational speed sensor and bearing device - Google Patents

Abstract

(57) Abstract: [PROBLEMS] To make a rotation speed sensor, which effectively utilizes an annular space and obtain a high output, inexpensive and easy to manufacture. An electromagnetic pickup having an L-shaped cross section and an electromagnetic pickup facing a gear sensing rotor.
An annular permanent magnet 3 for contacting the magnetic pole surface at one end with the collar 2b of the magnetic pole piece, and a coil 5 wound around the outer circumference of the cylindrical portion of the magnetic pole piece 2.
And a cover 6 made of a ferromagnetic material that serves as a return path of magnetic flux and a resin member 9 for fixing these, and the unevenness 2c, 2d and 12
The a and 12b are opposed to each other so that the strength of the magnetic flux coupling is changed by the rotation of the rotor over the entire area of the ring. This rotation speed sensor is easy to process the pole piece, does not require strict assembly accuracy, and has higher output than conventional products.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotational speed sensor for detecting the rotational speeds and rotational speeds of various rotating bodies such as automobile wheels using a sensing rotor and an electromagnetic pickup facing the rotor and a sensor therefor. The present invention relates to a bearing device equipped with.

[0002]

2. Description of the Related Art A rotation speed sensor to be mounted on a bearing device of an automobile is disclosed in, for example, Japanese Patent Application Laid-Open No. 63-166601. FIG. 5 shows an example. This rotational speed sensor is composed of an electromagnetic pickup 30 in which a coil 32 is wound around the outer circumference of a rod-shaped magnetic pole element 31 so that the magnetic flux of a permanent magnet 33 flows through the magnetic pole element 31, and a sensing rotor 12 facing the electromagnetic pickup 30. The sensing rotor 12 is a ferromagnetic gear wheel in which concavities and convexities are alternately formed in a circumferential direction on a surface facing the magnetic pole piece 31 at a predetermined pitch. The rotation of the sensing rotor 12 causes a change in the strength of magnetic flux coupling between the sensing rotor 12 and the magnetic pole piece 31, and the coil 32 of the electromagnetic pickup.
Then, induced electromotive force corresponding to the rotation speed of the sensing rotor 12 is generated. Therefore, the axle 15 that rotates integrally with the sensing rotor 12 based on the frequency of the output voltage of the electromagnetic pickup.
It is possible to obtain the rotation speed or the number of rotations.

In addition to this, as a rotation speed sensor having an annular magnetic pole piece, for example, as disclosed in Japanese Patent Laid-Open No. 264562/1993, inner and outer teeth are arranged at a constant pitch on the open end surface of the annular slot. An electromagnetic pickup consisting of a formed magnetic pole having a U-shaped cross section, an annular coil assembled in the slot of this magnetic pole, and a magnet sensing rotor in which magnetized portions of different polarities are alternately provided in the circumferential direction. There is one that is composed.

Further, as disclosed in Japanese Patent Application Laid-Open No. 7-120487, an electromagnetic pickup having a structure in which an annular magnet and a coil are sandwiched by two annular magnetic poles having different diameters, and a sensing rotor facing the electromagnetic pickup. Some are organized.

[0005]

A rotation speed sensor using a rod-shaped magnetic pole element has a sensing rotor 12 as shown in FIG.
Is fixed to the axle 15 or the like, and the electromagnetic pickup 30 is used by being exposed to the inside from the cover 18. In the case of this method,
It is difficult to expect high output because the electromagnetic pickup has to be made small due to space limitations.

Further, the rotation speed sensor using the annular magnetic pole having a U-shaped cross section can obtain a high output, but on the other hand, the magnetic pole is complicated and difficult to process, and cannot be manufactured inexpensively.

The rotational speed sensor in which the electromagnetic pickup has a structure in which an annular magnet is sandwiched by two magnetic poles is developed for the purpose of eliminating the drawbacks of the two types of sensors described above. If the phase of the unevenness formed in 1 is out of phase, the output decreases, and therefore, assembly accuracy is required, which is a bottleneck in further improving mass productivity and cost reduction.

[0008] Therefore, an object of the present invention is to make a rotational speed sensor, which uses an annular magnetic pole piece and can obtain a high output in a limited space, cheaper and easier to manufacture.

[0009]

In order to solve the above-mentioned problems, the rotation speed sensor of the present invention comprises an electromagnetic pickup facing the gear sensing rotor as follows.
That is, the electromagnetic pickup has a magnetic pole piece, a magnet, a coil, and a resin member for fixing these functional parts. The magnetic pole piece has an annular shape concentric with the sensing rotor and has a cross section at the rear of the cylindrical portion. The magnet is a ferromagnet having an L-shaped brim and having concave and convex portions alternately arranged at a front end facing the sensing rotor at a predetermined pitch. Is magnetized so as to have a pole, and one end is in contact with the brim of the magnetic pole piece, and the coil is wound around the outer circumference of the annular magnetic pole piece.

This rotation speed sensor is provided with a cover made of a ferromagnetic material for covering the functional parts of the electromagnetic pickup, and the cover has a cylindrical portion extending from the position surrounding the magnet to the outer peripheral portion of the coil. It is preferable to have the configuration. Further, it is more preferable that the cover has an end wall bent inward, and the end wall is in contact with the end surface of the magnet opposite to the pole piece contact surface.

In the bearing device of the present invention, the above-mentioned electromagnetic pickup of the rotation speed sensor is attached to the outer ring, and the sensing rotor, which is opposed to the electromagnetic pickup with a predetermined gap maintained, is supported on the outer ring through rolling elements. It is configured by being attached to a rotating member.

[0012]

Since the rotational speed sensor of the present invention uses the annular magnet and the magnetic pole piece which are concentric with the sensing rotor, the facing surface area of the magnetic pole piece and the sensing rotor is larger than that of the rotational speed sensor which uses the rod-shaped magnetic pole piece. Large, you can effectively use the installation space that is limited to an annular shape due to the presence of axles etc.
High output can be obtained.

Further, the pole piece has a cross section L composed of a cylindrical portion and a collar.
In the shape of a letter, the rear flange is in contact with the magnet, and by this flange, most of the magnetic flux flowing from the magnet can be guided to the sensing rotor, and a more effective magnetic circuit with less loss is configured and output. Is even higher.

Further, unlike the U-shaped cross-section pole piece which is difficult to manufacture, the pole piece having an L-shaped cross section can be manufactured by the forging method which is excellent in mass productivity, and the material cost and the processing cost can be reduced.

Further, since only one magnetic pole piece having unevenness is used, the phase matching of the unevenness is not required and the assembling becomes easy.

Since the cover provided with the ferromagnetic cover serves as a path for the magnetic flux returning from the sensing rotor to the magnet, the effect of reducing the loss of the magnetic circuit is enhanced and the output can be further increased. If the end wall of the cover is provided and the end wall is brought into contact with the end surface of the magnet opposite to the magnetic pole contact surface, there is no gap between the cover and the magnet to increase the magnetic resistance. The effect of high output by reduction is particularly large.

Further, since the bearing device of the present invention takes advantage of the characteristics of the rotational speed sensor incorporated integrally, it is more advantageous in productivity and cost than the conventional products, and the performance relating to rotation detection is also improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a specific example of the rotation speed sensor of the present invention. In the figure, 1 is an electromagnetic pickup, and 12 is a sensing rotor.

The electromagnetic pickup 1 comprises an annular magnetic pole piece 2 which is concentric with the sensing rotor 12, an annular permanent magnet 3, which is also concentric with the sensing rotor 12, a resin bobbin 4, a coil 5, a ferromagnetic cover 6, and a coil. Relay terminals 7 at both ends of
It is composed of a signal line 8 for taking out an output, which is connected via a line, and a resin member 9 which integrates the above-mentioned components.

The pole piece 2 is made of a ferromagnetic material, has a collar 2b on the outer periphery of the rear portion of the cylindrical portion 2a, and has an L-shaped cross section. In addition, the cylindrical portion 2a of this magnetic pole piece
Concavities and convexities 2c and 2d for changing the strength of the magnetic flux coupling are alternately provided at a predetermined pitch in the circumferential direction at the tip of the, i.e., the surface facing the sensing rotor.

The permanent magnet 3 has an inner diameter equal to that of the cylindrical portion 2a.
The inner diameter of the collar 2b and the outer diameter of the collar 2b are substantially matched with each other, and magnetized so as to have S and N poles at both axial ends, and one end (one magnetic pole surface) of the collar 2b is attached to the rear part It is in close contact.

The coil 5 is provided on the outer periphery of the cylindrical portion 2a of the pole piece. The coil 5, the magnetic pole piece 2 and the permanent magnet 3 are integrated in advance by a resin bobbin 4 (hereinafter, this integrated product is referred to as a functional component unit). Here, this functional component unit is covered by a cylinder of a cover 6. Then, the insertion-type relay terminal 7 is inserted into the socket 6 (not shown) in the bobbin (not shown), and the resin member 9 is molded. Then, the necessary parts are sealed with this resin member 9,
The cover 6, the functional component unit, and the signal line 8 are fixed.

The sensing rotor 12 is a ferromagnetic gear. The sensing rotor 12 has a spur gear-like shape in which irregularities 12a and 12b are provided at the same pitch as the irregularities 2c and 2d on the outer circumference thereof, and a ring-shaped ridge or bent portion facing the tip of the pole piece 2 is provided. It may be either one having irregularities formed thereon.

The relay terminal 7 is, as shown in FIG.
If it is provided on the end surface of the bobbin 4, the insertion of the bobbin into the cover 6 will not be obstructed by the terminal, so that the bobbin can be fixed to the bobbin 4 in advance.

In the electromagnetic pickup 1 shown in FIG. 1, the end wall 6b of the cover 6 which is bent inward is separated from the permanent magnet 3, but as shown in FIG. When it is brought into contact with the surface on the side opposite to the contact surface of the magnetic pole piece, the magnetic resistance between the cover and the magnet is reduced, and the flow of the magnetic flux returning through the cover becomes smooth.

In addition to this, as shown in FIG.
Alternatively, the connector 10 may be provided to connect the signal line to the coil terminal 11.

FIG. 4 shows an example in which the rotation speed sensor adopting the electromagnetic pickup 1 of FIG. 2 is assembled to the bearing device 13 (the so-called hub unit for an automobile). In this bearing device 13, an axle 15 integrated with a hub 14 is supported by an outer ring 17 via a rolling element (ball) 16 with a retainer, and the extended end of the cover 6 is fixed to the outer periphery of the outer ring 17. Then, the electromagnetic pickup 1 is supported by the outer ring 17, and the magnetic pole piece 2 is attached to the sensing rotor 12 fixed to the axle 15.
Are opposed to each other with a predetermined gap maintained.

In this bearing device 13, the magnetic flux from the permanent magnet 3 is guided to the magnetic pole piece 2 and flows into the sensing rotor 12, and from this sensing rotor 12 to the axle 15,
Magnetic flux flows to the cover 6 via the rolling elements 16 and the outer ring 17, and further via the space, and returns to the magnet 3 along the cover. This flow of magnetic flux occurs over the entire outer circumference of the axle 15, and therefore a higher output than that of the device of FIG. 5 is obtained. Since the cover 6 of the bearing device 13 is in a state of holding the functional parts of the electromagnetic pickup, the bearing device 13 is superior in stationary stability of the electromagnetic pickup as compared with the conventional device of FIG. 5, and stable detection can be performed. It

[0029]

As described above, the rotational speed sensor of the present invention is easy to manufacture because the shape of the magnetic pole piece is simplified and it is not necessary to correspond to the unevenness.

Further, the material cost, the processing cost and the assembly cost can be reduced and the mass production effect can be expected, so that the price can be reduced.

Further, since the system utilizes the annular space effectively, a high output can be obtained and the detection performance is excellent.

The one having a ferromagnetic cover and the one having the end wall of the cover brought into contact with the end face of the magnet have a high effect of increasing the output and the sperm precision is further improved.

Further, since the bearing device of the present invention employs the rotation speed sensor that produces the above-mentioned actions and effects,
It has advantages in productivity, cost, and performance compared to conventional products.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a rotation speed sensor of the present invention.

FIG. 2 is a sectional view showing another example of an electromagnetic pickup.

FIG. 3 is a sectional view of still another example of the electromagnetic pickup.

FIG. 4 is a sectional view showing an example of a bearing device of the present invention.

FIG. 5 is a sectional view of a bearing device using a conventional rotation speed sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electromagnetic pickup 2 Pole piece 2a Cylindrical part 2b Collar 2c Recessed part 2d Convex part 3 Permanent magnet 4 Resin bobbin 5 Coil 6 Cover 7 Relay terminal 8 Signal line 9 Resin member 10 Connector 11 Coil terminal 12 Sensing rotor 12a Recessed part 12b Convex part 13 Bearing device 14 Hub 15 Axle 16 Rolling element 17 Outer ring

Claims (4)

[Claims] 1. A rotation speed sensor comprising a sensing rotor and an electromagnetic pickup facing the sensing rotor, wherein an induced electromotive force according to the rotation speed of the sensing rotor is generated in a coil of the electromagnetic pickup, wherein the electromagnetic pickup has a pole piece. A magnet, a coil, and a resin member for fixing these functional parts, and the magnetic pole has an annular ring concentric with the sensing rotor, and has a collar having an L-shaped cross section at the rear of the cylindrical portion, Further, the magnet is made of a ferromagnetic material having concavities and convexities alternately at a front end facing the sensing rotor at a predetermined pitch, and the magnet is an annular ring concentric with the sensing rotor and is magnetized to have respective poles at both axial ends. A rotation speed sensor, wherein one end is in contact with a collar of the magnetic pole piece, and the coil is wound around an outer circumference of the annular magnetic pole piece. 2. A ferromagnetic cover for covering the functional parts of the electromagnetic pickup is provided, and the cover has a cylindrical portion extending from a position surrounding the magnet to an outer peripheral portion of the coil. The rotation speed sensor according to claim 1, wherein 3. The cover according to claim 2, wherein the cover has an inwardly bent end wall, and the end wall is in contact with the end surface of the magnet opposite to the magnetic pole contact surface. Rotation speed sensor. 4. The electromagnetic pickup of the rotational speed sensor according to claim 1, wherein an electromagnetic pickup is attached to an outer ring, and a sensing rotor facing the electromagnetic pickup with a predetermined gap is provided on the outer ring. A bearing device attached to a rotating member supported through the bearing.